FAULT DETECTING SYSTEM

摘要

PURPOSE:To decide quickly a faulty line concentration multiplex part producing a fault by an overall decision obtained from the result of both collation test and signal return test. CONSTITUTION:The test digital signal is sent back to line concentration multiplex parts CSW0 and CSW1 via a return circuit RP and then sent to a selecting circuit SEL2 via channels P1 and P2. Then only the test digital signal sent from the using line concentration multiplex part CSW0 is selected and sent back to a distribution stage channel network DSW. A test circuit TST compares the sent- back test digital signal with the transmitted original digital signal. When the coincidence is obtained from the comparison, it is decided that the circuit RP is normal. While a fault is decided if no coincidence is obtained. Therefore a fault is discriminated between the parts CSW0 and CSW1 based on the result of the signal return test if a collating circuit M1 or M2 detects no coincidence from the above-mentioned comparison.